​Through the years, I gathered a few Go-to Websites that I use weekly as Do Nows for my students. One of my favorites is Estimation 180. This website gives students various estimation challenges that build student number sense and problem solving skills. The website is run by a middle school teacher, Andrew Stadel. He is very popular in the I Teach MathTwitter Community. (I’ve also taken a few courses with his pals Dan Meyer, Graham Fletcher and Robert Kaplinsky. I thank them all very much for making me a better math teacher).

Estimation is a very challenging skill for elementary grade students, and yet I find it to be the most important skill to teach. We survive life through estimation: Do we have enough money? How much paint should I purchase? Is this enough fabric? How many copies should I make?I think we all see the point. However, with students they live for the exact. I notice that my fourth graders are most reluctant to make estimations than my fifth graders. Specifically, I’m trying to change their mindset that estimation is a guess, but rather logically and mathematically reasoning.

The Estimation challenges are photos of various items, people, or things. Students are asked to guess how many, or how tall, or how long something may be. The photograph always gives enough clues for students to make a reasonable estimate-using math. For example, in the very first challenge, Mr. Stadel is standing next to a fence. Students must figure out how tall Mr. Stadel is using the information provided in the photo as well as prior knowledge. In the various subsequent challenges, we use the knowledge of Mr. Stadel’s height to figure out the height of the rest of his family, and even his Christmas tree. I love how the challenges build on one another; this helps students to use math, rather than just a guess. In addition, each challenge requests students to make a low estimate, high estimate, and reasonable estimate with an explanation of their thinking. My students are very comfortable with this process.

Recently, my fourth grade students worked through the following challenges:​

The objective of these challenges are for students to estimate the value of each glass container of coins. Working through the very first challenge with pennies was a "doozy." They simply did not know where to start. I noticed through explanations that all 26 students guessed. This is very surprising that they did not have prior knowledge of rolling coins. The scaffolding started there. Just like in reading I wanted to build some prior knowledge. We talked about what we knew about a penny: the size and value. We established vocabulary of what a “roll” and “container” meant in this challenge. From there we determined an estimate for how many pennies in a roll and how many rolls do we think are in the container? We followed this process throughout the challenges.

Overall, my students did better with each challenge, and some felt comfortable with the stated process; more than half continue to display difficulty. Explanations lacked reasoning, but guessing. And some students had troubling explaining how they received the value of each container. My biggest take away is that some students simply were not listening to strategies from other students and their learning did not progress. If they were confused they didn't ask questions. As much as I had other students reiterate was they learned from their peers, some just weren’t absorbing what was happening in these very similar problems. ​

As a result, I realized the importance of continued practice with estimation and tasks like these. I understand that the fear and frustration of slow growth may deter teachers from continuing to provide these types of tasks during whole group instruction but rather use it as an enrichment for children who finish early. I look at it differently. This is important. This builds number sense. This is a must. Perhaps visiting Estimation180 one time a week is not enough and maybe I need to increase time spent on it?

I believe that all types of learners can be successful with Estimation180; I just need to adjust the way in which it’s scaffolded based on the needs of the class. Strategies that I’ve implemented with my fourth graders since the stated tasks include :

Performing a “What do I Notice in the picture and how can it help me?” prior to sending children off to work in pairs or independently.

Having children write reflections on what they learned after the discussion. Did students pick up on big key ideas?

Creating a visual activity sheet for students to complete to guide thinking, rather than using a blank sheet in the notebook.

Reiteration of what they understand from a friend, as well as when confusion happens, they state the last thing they understood.

These strategies increased student success. I'm optimistic that with continued practice, my students' critical thinking skills will improve. The best part is that even with the struggle, the kids still enjoy our Wednesday with Estimation 180. If you have additional comments and/or suggestions, do not hesitate to reach out.